Tape reel and information recording medium

ABSTRACT

A tape reel includes a first flange, a cylindrical body, and a second flange formed separately. The first flange, the cylindrical body, and second flanges are joined with inner surfaces of the first and second flanges contacting the cylindrical body. Joining pins are erected on the inner surface of the first flange. The cylindrical body includes an outer wall, bosses with through-holes for the joining pins fixed to the inside of the outer wall, and an inner wall positioned inside and following the outer wall. The second flange has an opening formed in the center and a protrusion at an opening edge protruding toward the center and including through-holes through which the joining pins are inserted. Plural positioning pins that contact an outer surface of the inner wall in a state where the cylindrical body is contacted to position the cylindrical body are formed on the first and/or second flange.

1. FIELD OF THE INVENTION

The present invention relates to a tape reel around which a magnetictape for recording information is wound and to an information recordingmedium equipped with such tape reel.

2. DESCRIPTION OF THE RELATED ART

As one example of this type of tape reel, a tape reel assembly(hereinafter simply “tape reel”) disclosed in Japanese Laid-Open PatentPublication No. 2001-118358 is known. This tape reel is used in a singlereel-type information recording medium and includes an upper flange, alower flange, and a hub ring. The upper flange, the lower flange, andthe hub ring are formed separately (manufactured separately), with suchparts being joined and assembled in a state where the hub ring has beenpositioned between the upper flange and the lower flange to construct atape reel. Also, with such tape reel, by having bosses formed on bothflanges engage notches formed in inner circumferential edges at bothends of the hub ring, rotation of the hub ring with respect to theflanges is restricted.

As one example, with a construction where the lower flange and the hubring are integrally formed, when pressure is applied to the hub ring dueto a magnetic tape tightening when the tape is wound on, the hub ringdeforms so as to become squeezed (i.e., the diameter falls). In keepingwith this, the outer circumferential edge of the lower flange becomestilted toward the upper flange, and as a result, there is the risk ofboth flanges approaching one another and of contact between therespective flanges and the sides of the tape. On the other hand, withthe tape reel described above, by forming the upper flange, the lowerflange, and the hub ring separately, compared to a construction wherethe lower flange and the hub ring are integrally formed, for example,even if the hub ring deforms so as to become squeezed, such deformationis unlikely to directly cause deformation of the flange. This tape reelis therefore somewhat capable of preventing situations where there iscontact between the sides of a magnetic tape and the flanges when thetape is wound on and/or difficulty in winding on a magnetic tape due tothe gap between the two flanges narrowing.

SUMMARY OF THE INVENTION

However, as a result of investigating the conventional tape reeldescribed above, the present inventors discovered the following problemwith the conventional tape reel. That is, with the tape reel describedabove, notches formed in inner circumferential edges at both ends of thehub ring and bosses formed in the respective flanges are caused toengage one another. In the engaged state, the positions where thenotches are formed at both ends of the hub ring are positioned outsidethe bosses. This means that when the hub ring deforms so as to becomesqueezed due to the magnetic tape being tightened, there is the risk ofthe parts where the notches are formed applying pressure to the bossesand such pressing forces causing the flanges to deform. Accordingly,with the conventional tape reel, as before there is still the problem ofthe sides of the tape contacting the flanges when the magnetic tape iswound on and/or the gap between the two flanges narrowing and making itdifficult to wind on a magnetic tape.

The present invention was conceived in view of the problem describedabove and it is a main object of the present invention to provide a tapereel and an information recording medium capable of reliably preventingdeformation of the flanges due to tightening of a magnetic tape when themagnetic tape is wound on.

To achieve the stated object, a tape reel according to the presentinvention comprises a first flange, a cylindrical body, and a secondflange that are formed as separate objects, wherein the tape reel isconstructed by joining the first flange, the cylindrical body, and thesecond flange in a state where an inner surface side of the first flangeand an inner surface side of the second flange are in contact with thecylindrical body and face one another, the first flange includes joiningpins erected on the inner surface of the first flange, the cylindricalbody includes an outer circumferential wall, bosses which are fixed tothe outer circumferential wall on an inside of the outer circumferentialwall and in which through-holes through which the joining pins areinserted are formed, and an inner wall which is positioned inside theouter circumferential wall and disposed so as to follow the outercircumferential wall, the second flange has an opening formed in acentral portion thereof and includes a protruding portion that is formedat an edge portion of the opening so as to protrude toward a center ofthe opening and includes through-holes through which the joining pinsare inserted, and on at least one of the first flange and the secondflange, a plurality of positioning pins that contact a surface on anouter circumferential wall side of the inner wall in a state where thecylindrical body is contacted by at least one of the first flange andthe second flange to position the cylindrical body are formed.

Also, an information recording medium according to the present inventioncomprises the tape reel described above.

According to the tape reel and the information recording medium, thecylindrical body is constructed so as to include the bosses, in whichthe through-holes through which the joining pins erected on the firstflange are inserted are formed, and the inner wall, the second flange isconstructed so as to include the protruding portions including thethrough-holes through which the joining pins are inserted, and aplurality of the positioning pins that contact the surface on the outercircumferential wall side of the inner wall to position the cylindricalbody are formed on the first flange. By doing so, even if the outercircumferential wall has deformed so as to become squeezed due topressure applied by tightening of a magnetic tape when the magnetic tapeis wound on, it is possible to maintain a state where pressure is notapplied to the joining pins and the positioning pins. Therefore,according to the tape reel and the information recording medium, sinceit is possible to reliably prevent deformation of the first flange andthe second flange due to pressure being applied to the joining pinsand/or the positioning pins, it is possible to reliably prevent contactbetween the sides of a magnetic tape and the first flange and secondflange when the magnetic tape is wound on.

Also, in the tape reel according to the present invention, the edgeportion of the second flange may be formed in a cylindrical shape thatprotrudes toward the first flange and fits inside the outercircumferential wall, the protruding portion may be formed at a frontend portion of the cylindrical edge portion, and the cylindrical body isjoined to the second flange in a state where an end surface on a secondflange side of at least one of the bosses and the inner wall contactsthe protruding portion and an end surface on the second flange side ofthe outer circumferential wall is apart from the inner surface of thesecond flange.

By using such construction, even if the second flange is pressed ontothe cylindrical body when the first flange, the cylindrical body, andthe second flange are joined, a pressing force in the direction from thefirst flange toward the second flange does not act from the outercircumferential wall of the cylindrical body onto the second flange.This means it is possible to sufficiently suppress deformation where theouter circumferential edge of the second flange becomes outwardly openedaway from the outer circumferential edge of the first flange. As aresult, according to the tape reel and the information recording medium,it is possible to reliably avoid a situation where, due to the outercircumferential edge of the second flange being outwardly opened, amagnetic tape becomes wound on the tape reel in a state where the endsin the width direction of the magnetic tape are not aligned (a statewhere the tape reel is not properly wound on with the end portions ofthe magnetic tape in alignment), which can cause creasing of the tape,improper rotation of the tape reel, recording/reproduction errors, andthe like.

Also, in the tape reel according to the present invention, a thickenedportion that protrudes toward the second flange side and fits inside theouter circumferential wall may be formed on the inner surface of thefirst flange, and the cylindrical body may be joined to the first flangein a state where an end surface on the first flange side of at least oneof the bosses and the inner wall contacts the thickened portion and anend surface on the first flange side of the outer circumferential wallis away from the inner surface of the first flange.

By using such construction, even if the cylindrical body is pressed ontothe first flange when the first flange, the cylindrical body, and thesecond flange are joined, the pressure will act upon the thickenedportion that has high rigidity, making it possible to sufficientlysuppress deformation where the outer circumferential edge of the firstflange becomes outwardly opened away from the outer circumferential edgeof the second flange. As a result, according to the tape reel and theinformation recording medium, it is possible to reliably prevent asituation where creasing of the tape, improper rotation of the tapereel, recording/reproduction errors, and the like occur due to the outercircumferential edge of the first flange becoming outwardly opened.

Also, in the tape reel according to the present invention, thepositioning pins may be formed on both the first flange and the secondflange.

By using such construction, it is possible to more reliably position thecylindrical body with respect to the first flange and the second flange.

Also, in the tape reel according to the present invention, the bossesand the inner wall may be joined, and the inner wall may be fixed to theouter circumferential wall via the bosses.

By using such construction, it is possible to sufficiently increase thestrength of the inner wall.

It should be noted that the disclosure of the present invention relatesto a content of Japanese Patent Application 2010-211600 that was filedon 22 Sep. 2010 and the entire content of which is herein incorporatedby reference.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention will beexplained in more detail below with reference to the attached drawings,wherein:

FIG. 1 is an exploded perspective view of an information recordingmedium;

FIG. 2 is a perspective view of a tape reel;

FIG. 3 is a plan view of the tape reel;

FIG. 4 is an exploded perspective view of the tape reel in a state wherea first flange is at the bottom;

FIG. 5 is an exploded perspective view of the tape reel in a state wherea second flange is at the bottom;

FIG. 6 is a plan view of the first flange;

FIG. 7 is a plan view of a cylindrical body;

FIG. 8 is a plan view of the second flange;

FIG. 9 is a plan view of a state where the cylindrical body has beenfitted into the first flange;

FIG. 10 is a cross-sectional view along a line A-A in FIG. 3;

FIG. 11 is an enlarged view of a region B in FIG. 10;

FIG. 12 is an enlarged view of a region C in FIG. 10; and

FIG. 13 is a plan view of another second flange.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of a tape reel and an information recording mediumaccording to the present invention will now be described with referenceto the attached drawings.

First, the construction of an information recording medium 1 will bedescribed with reference to the drawings.

The information recording medium 1 shown in FIG. 1 is a single-reel typeinformation recording medium used in a storage device for backing uprecording data that has been recorded in an electronic computer forexample, and as shown in the diagram, includes a case main body 2, atape reel 3, a brake releasing plate 4, a locking member 5, a brakespring 6, and a door member 7. Note that although in reality a magnetictape is wound around the tape reel 3 of the information recording medium1, for ease of understanding the construction of the respective parts,the magnetic tape has been omitted from FIG. 1.

As shown in FIG. 1, the case main body 2 includes a lower case 11 and anupper case 12 that are formed in shallow plate-like shapes and arecapable of fitting together, with the tape reel 3 being rotatablyenclosed in the internal space formed when the two cases 11, 12 arefitted together. Here, cutaway parts 11 a, 12 a that construct a tapewithdrawal opening 2 a for pulling the magnetic tape wound around thetape reel 3 out of the case main body 2 are respectively formed in thelower case 11 and the upper case 12.

As shown in FIGS. 4 and 5, the tape reel 3 includes a first flange 21, acylindrical body 22, and a second flange 23 that are separately formed,and is capable of having a magnetic tape wound thereon. As shown inFIGS. 2 to 5 and 10, the tape reel 3 is assembled with an inner surface21 a side of the first flange 21 positioned on an end portion 22 a sideof the cylindrical body 22, an inner surface 23 a side of the secondflange 23 positioned on an end portion 22 b side of the cylindrical body22, the respective inner surface 21 a, 23 a sides in contact with thecylindrical body 22 in a facing state, and the first flange 21, thecylindrical body 22, and the second flange 23 joined to one another.

As shown in FIGS. 4 to 6, the first flange 21 is constructed in a discshape. Also, a thickened portion 21 c, which protrudes toward the secondflange 23 in the facing state described above and fits inside an outercircumferential wall 41 of the cylindrical body 22, is formed in acentral portion of the inner surface 21 a (the upper surface in FIG. 4)of the first flange 21. Here, as shown in FIG. 11, the thickened portion21 c is formed so that a protruding length L1 from the inner surface 21a of the first flange 21 (i.e., the thickness of the thickened portion21 c) is greater than a step height L2 of the cylindrical body 22,described later. Also, three toothed portions 31, which are arc-shapedwhen viewed from above and capable of meshing the locking member 5 thatis energized by the brake spring 6 (both shown in FIG. 1), are formed onthe thickened portion 21 c of the first flange 21. Three through-holes34 for attaching the brake releasing plate 4 so as to be capable ofmoving up and down are also formed in the first flange 21.

As shown in FIGS. 4 and 6, a plurality (for example, six) of joiningpins 32 for joining the first flange 21, the cylindrical body 22, andthe second flange 23 and restricting rotation of the second flange 23with respect to the first flange 21 and the cylindrical body 22 areerected on the thickened portion 21 c of the first flange 21. In thiscase, the positions where the joining pins 32 are erected are set sothat as shown in FIG. 9, in a state where the inner surface 21 a side ofthe first flange 21 contacts the cylindrical body 22, the joining pins32 are positioned to the inside (i.e., toward the center of thecylindrical body 22) of the outer circumferential wall 41 of thecylindrical body 22 and pass through through-holes 42 a of bosses 42(see FIGS. 4 and 7) formed on the cylindrical body 22. The length of thejoining pins 32 is set longer than the total of the length of the bosses42 and the thickness of protruding portions 52 (see FIG. 8) of thesecond flange 23. From the viewpoints of achieving sufficient strengthand preventing sink marks during molding, a diameter (outer diameter) D1of the joining pins 32 (see FIG. 11) should preferably be in a range of1.2 mm to 2.0 mm, inclusive. As one example, with the tape reel 3, thejoining pins 32 are formed so that the diameter D1 thereof is 1.6 mm.

Also, as shown in FIG. 9, a plurality (for example, six) of positioningpins 33 for contacting outer surfaces 43 a of inner walls 43 of thecylindrical body 22 to position the cylindrical body 22 in a state wherethe inner surface 21 a side contacts the cylindrical body 22 are formedon the inner surface 21 a of the first flange 21. Here, to facilitateattachment of the cylindrical body 22 to the first flange 21 whenassembling the tape reel 3, the positioning pins 33 are formed so thatthe diameter of the front end portions thereof is smaller than thediameter of the base end portions (i.e., the positioning pins 33 aretapered).

In addition, as shown in FIG. 5, a metal plate 35 is attached to anouter surface 21 b (the upper surface in FIG. 5) of the first flange 21to enable the drive shaft of a drive apparatus, not shown, tomagnetically attract the tape reel 3. A ring-shaped toothed portion 36that is capable of meshing a toothed portion of the drive shaft of thedrive apparatus is formed on the outer surface 21 b of the first flange21 so as to surround the metal plate 35.

As shown in FIGS. 4, 5, and 7, the cylindrical body 22 is formed in acylindrical shape and is constructed so that a magnetic tape can bewound around an outer surface 41 a side of the outer circumferentialwall 41. A plurality of (for example, six) bosses 42, in whichthrough-holes 42 a through which the joining pins 32 of the first flange21 can pass through are formed, are also disposed on the inside (i.e.,toward the center of the cylindrical body 22) of the outercircumferential wall 41. The respective bosses 42 are disposed at equalintervals around an inner surface 41 b of the outer circumferential wall41 and are fixed to the outer circumferential wall 41 via ribs 42 b (seeFIGS. 5, 7). In this case, as shown in FIG. 11, the through-holes 42 aof the bosses 42 are formed so that a diameter (inner diameter) D2thereof is larger than the diameter D1 of the joining pins 32 so as toproduce gaps (clearances) between the inner surfaces of thethrough-holes 42 a and the outer circumferential surfaces of the joiningpins 32 when the joining pins 32 have been inserted. More specifically,the through-holes 42 a are formed so that the diameter D2 thereof isaround 0.2 mm to 1.0 mm larger than the diameter D1 of the joining pins32 so that the gaps described above are in a range of 0.1 mm to 0.5 mm,inclusive. As one example, in the tape reel 3, the through-holes 42 aare formed so that the diameter D2 thereof is 2.2 mm.

Also, as shown in FIGS. 4, 5, and 7, a plurality of (for example, three)inner walls 43 that are arc-shaped when viewed from above are disposedfurther inside than the outer circumferential wall 41 so as to followthe outer circumferential wall 41 and face the inner surface 41 b of theouter circumferential wall 41 at a distance from the inner surface 41 b.Both end portions of each of the inner walls 43 are connected to two ofthe bosses 42. That is, each inner wall 43 is fixed to the outercircumferential wall 41 via two bosses 42. A reinforcing rib 43 b in theform of a half cylinder is also formed in a central portion of eachinner wall 43. Here, by forming the reinforcing ribs 43 b, it ispossible to increase the strength of the inner walls 43 and, by havingejection pins contact the end surfaces of the reinforcing ribs 43 b whenremoving the cylindrical body 22 from a mold during injection molding ofthe cylindrical body 22, it is also possible to reliably remove thecylindrical body 22 from the mold without damaging the inner walls 43.

Also, as shown in FIG. 5, on the cylindrical body 22, end surfaces 42 con the end portion 22 a side of the bosses 42 are formed so as to beflush with the end surfaces 43 c on the end portion 22 a side of theinner walls 43. Also, as shown in FIG. 4, end surfaces 42 d on the endportion 22 b side of the bosses 42 are formed so as to be flush with endsurfaces 43 d on the end portion 22 b side of the inner walls 43. Thatis, the bosses 42 and the inner walls 43 are formed so that the heightsthereof (that is, the lengths along the thickness direction of the tapereel 3) are the same. In addition, as shown in FIG. 10, the height ofthe outer circumferential wall 41 is formed on the cylindrical body 22so as to be higher than the heights of the bosses 42 and the inner walls43. In this case, as shown in FIG. 11, the cylindrical body 22 is formedso that the step height L2 between the end surface 41 c of the outercircumferential wall 41 on the end portion 22 a side and the endsurfaces 42 c of the bosses 42 and the end surfaces 43 c of the innerwalls 43 on the end portion 22 a side (i.e., the length from the endsurface 41 c to the end surfaces 42 c, 43 c) is shorter than theprotruding length L1 of the thickened portion 21 c of the first flange21 described above. This means that as shown in FIG. 11, the cylindricalbody 22 is joined to the first flange 21 in a state where the endsurfaces 42 c of the bosses 42 and the end surfaces 43 c of the innerwalls 43 positioned on the first flange 21 side contact the surface ofthe thickened portion 21 c and the end surface 41 c of the outercircumferential wall 41 positioned on the first flange 21 side and theinner surface 21 a of the first flange 21 are apart.

Also, as shown in FIG. 12, the cylindrical body 22 is formed so that thestep height L3 between the end surface 41 d of the outer circumferentialwall 41 on the end portion 22 b side and the end surfaces 42 d of thebosses 42 and the end surfaces 43 d of the inner walls 43 on the endportion 22 b side (that is, the length from the end surface 41 d to theend surfaces 42 d, 43 d) is shorter than the length L4 from the innersurface 23 a of the second flange 23 to inner surfaces 52 b of theprotruding portions 52, described later.

As shown in FIGS. 4, 5, and 8, the second flange 23 is constructed in adisc shape. The second flange 23 also has a circular opening 51 formedin a center thereof. An edge portion 51 a of the opening 51 protrudesdownward (i.e., in a direction toward the first flange side) and isformed in a cylindrical shape so as to fit inside the outercircumferential wall 41 of the cylindrical body 22 in the assembledstate. In addition, on a front end portion (lower end portion) of theedge portion 51 a, a plurality of (for example, six) protruding portions52 that protrude toward the center of the opening 51 are formed at equalintervals apart around the edge portion 51 a. Through-holes 52 a,through which the joining pins 32 formed on the first flange 21 arecapable of being inserted, are also formed in the protruding portions52. In this case, as shown in FIG. 12, in the same way as thethrough-holes 42 a of the bosses 42 on the cylindrical body 22 describedabove, the through-holes 52 a of the protruding portions 52 are formedso that a diameter (inner diameter) D3 thereof is around 0.2 mm to 1.0mm larger than the diameter D1 of the joining pins 32 to produce gaps ina range of 0.1 mm to 0.5 mm, inclusive, between the inner surfaces ofthe through-holes 52 a and the outer circumferential surfaces of thejoining pins 32. As one example, in the tape reel 3, the through-holes52 a are formed so that the diameter D3 thereof is 2.2 mm.

Also, as shown in FIG. 12, the second flange 23 is formed so that thelength L4 from the inner surface 23 a of the second flange 23 to theinner surfaces 52 b of the protruding portions 52 is longer than thestep height L3 between the end surface 41 d of the outer circumferentialwall 41 and the end surfaces 42 d of the bosses 42 and the end surfaces43 d of the inner walls 43 on the cylindrical body 22 described above.This means that as shown in FIG. 12, the cylindrical body 22 is joinedto the second flange 23 in a state where the end surfaces 42 d of thebosses 42 and the end surfaces 43 d of the inner walls 43 positioned onthe second flange 23 side contact the inner surfaces 52 b of theprotruding portions 52 and the end surface 41 d of the outercircumferential wall 41 positioned on the second flange 23 side and theinner surface 23 a of the second flange 23 are apart.

As shown in FIG. 1, the brake releasing plate 4 is constructed withthree leg portions 4 a that are capable of being inserted through thethrough-holes 34 formed in the first flange 21 of the tape reel 3erected on the rear surface thereof. By passing the leg portions 4 athrough the respective through-holes 34, the brake releasing plate 4 isdisposed inside the cylindrical body 22 of the tape reel 3 so as to beincapable of rotation but capable of moving up and down.

As shown in FIG. 1, the locking member 5 has toothed portions 5 a, whichare capable of meshing with the toothed portions 31 of the tape reel 3,formed on the bottom surface thereof. Here, the locking member 5 isenergized by the brake spring 6 and the toothed portions 5 a mesh withthe toothed portions 31 of the tape reel 3 to restrict rotation of thetape reel 3.

The brake spring 6 is constructed of a coil spring, is disposed betweenthe upper case 12 and the locking member 5, and energizes the lockingmember 5 toward the first flange 21 side of the tape reel 3. As shown inFIG. 1, the door member 7 is formed in the shape of a thin plate that iscapable of closing the tape withdrawal opening 2 a and is slidablyhoused in guide grooves respectively formed in a side wall of the lowercase 11 and a side wall of the upper case 12.

Next, one example method of assembling the tape reel 3 will bedescribed. First, as shown in FIG. 4, the first flange 21 is disposed onan assembly platform in a state where the inner surface 21 a facesupward. After this, in a state where the end portion 22 a of thecylindrical body 22 faces downward and the respective joining pins 32 ofthe first flange 21 are inserted through the respective through-holes 42a of the bosses 42 of the cylindrical body 22, the cylindrical body 22is pressed downward toward the first flange 21 to bring the cylindricalbody 22 into contact with the inner surface 21 a side of the firstflange 21. When doing so, as shown in FIG. 9, the positioning pins 33contact the outer surfaces 43 a of the inner walls 43 of the cylindricalbody 22 to position the cylindrical body 22. Also, as shown in FIG. 11,since the step height L2 between the end surface 41 c of the cylindricalbody 22 and the end surfaces 42 c, 43 c is shorter than the protrudinglength L1 of the thickened portion 21 c of the first flange 21, in suchstate the end surfaces 42 c, 43 c contact the surface of the thickenedportion 21 c and the end surface 41 c and the inner surface 21 a of thefirst flange 21 are apart. Also, since the length of the respectivebosses 42 is slightly shorter than the joining pins 32, in this statethe front end portions of the joining pins 32 protrude from the bosses42.

After this, while inserting the front end portions of the respectivejoining pins 32 that protrude from the bosses 42 through thethrough-holes 52 a of the protruding portions 52 of the second flange23, the second flange 23 is pressed down toward the cylindrical body 22to bring the inner surface (the lower surface in FIG. 4) side of thesecond flange 23 into contact with the cylindrical body 22. Here, asshown in FIG. 12, since the step height L3 between the end surface 41 dof the cylindrical body 22 and the end surfaces 42 d, 43 d is shorterthan the length L4 from the inner surface 23 a of the second flange 23to the inner surfaces 52 b of the protruding portions 52, in this statethe end surfaces 42 d, 43 d contact the inner surfaces 52 b of theprotruding portions 52 and the end surface 41 d and the inner surface 23a of the second flange 23 are apart. Also, since the length of thejoining pins 32 is longer than the total of the length of the bosses 42and the thicknesses of the protruding portions 52 of the second flange23, in this state, the front end portions of the joining pins 32protrude from the protruding portions 52. Next, by melting the front endportions of the joining pins 32 protruding from the protruding portions52 using an ultrasonic welding apparatus, the second flange 23 isfastened (crimped) to the cylindrical body 22. By doing so, the firstflange 21, the cylindrical body 22, and the second flange 23 are joinedvia the joining pins 32 to assemble the tape reel 3.

Here, as described above, during assembly of the tape reel 3, the endsurfaces 42 d, 43 d of the cylindrical body 22 contact the innersurfaces 52 b of the protruding portions 52 of the second flange 23 andthe end surface 41 d of the cylindrical body 22 and the inner surface 23a of the second flange 23 are apart. This means that when the firstflange 21, the cylindrical body 22, and the second flange 23 are joined(crimped), even if the second flange 23 is pressed onto the cylindricalbody 22, the pressure that acts from the first flange 21 toward thesecond flange 23 will not act from the outer circumferential wall 41 ofthe cylindrical body 22 onto the second flange 23, which makes itpossible to sufficiently suppress deformation where the outercircumferential edge of the second flange 23 becomes outwardly openedaway from the outer circumferential edge of the first flange 21. Also,as described above, during assembly of the tape reel 3, the end surfaces42 c, 43 c of the cylindrical body 22 contact the thickened portion 21 cof the first flange 21 and the end surface 41 c of the cylindrical body22 is apart from the inner surface 21 a of the first flange 21. Thismeans that when the cylindrical body 22 and the second flange 23 arejoined (crimped), even if the cylindrical body 22 is pressed onto thefirst flange 21, since such pressure will act upon the thickened portion21 c that has high rigidity, it is possible to sufficiently suppressdeformation that causes the outer circumferential edge of the firstflange 21 to become outwardly opened away from the outer circumferentialedge of the second flange 23. In addition, with the tape reel 3, thebosses 42 and the inner walls 43 are formed with the same heights, theend surfaces 42 c and the end surfaces 43 c are flush, and the endsurfaces 42 d and the end surfaces 43 d are also flush. This means thatthe area of contact between the bosses 42 and inner walls 43 of thecylindrical body 22 and the protruding portions 52 of the second flange23 and the area of contact between the bosses 42 and inner walls 43 ofthe cylindrical body 22 and the thickened portion 21 c of the firstflange 21 are large. As a result, the pressure applied when the firstflange 21, the cylindrical body 22, and the second flange 23 are joinedis dispersed and it is possible to sufficiently suppress deformation ofcertain parts due to the pressure being concentrated.

Next, the operation of the information recording medium 1 duringrecording and reproduction will be described with reference to thedrawings.

When the information recording medium 1 has been loaded in a driveapparatus, not shown, the drive apparatus slides the door member 7 toopen the tape withdrawal opening 2 a and pulls out the magnetic tape.Next, a tape reel on the drive apparatus side winds on the magnetic tapewhile a recording/reproduction unit of the drive apparatus carries outthe recording of data on the magnetic tape or the reading of recordeddata from the magnetic tape. After this, when the recording and/orreading of data has been completed, the drive apparatus rotates the tapereel 3 to start winding on the magnetic tape (i.e., rewinding themagnetic tape back onto the information recording medium 1). When doingso, to prevent slackening, as one example, the drive apparatus controlsthe rotation of the tape reel on the drive apparatus side to apply aconstant tension to the magnetic tape. By doing so, the magnetic tape iswound onto the tape reel 3. At this time, since tension is applied tothe magnetic tape, a certain degree of force toward the center isapplied to the outer circumferential wall 41 of the cylindrical body 22due to the tightening of the magnetic tape.

In this case, with the tape reel 3, since a gap of around 0.1 mm isproduced between the joining pins 32 of the first flange 21 and theinner circumferential walls of the through-holes 42 a of the bosses 42of the cylindrical body 22, even if there is deformation that squeezesthe outer circumferential wall 41 due to the pressure applied by thetightening of the magnetic tape, the joining pins 32 will remain in astate where pressure is not applied thereto from the outercircumferential wall 41 due to such squeezing. Also with the tape reel3, the positioning pins 33 contact the outer surfaces 43 a of the innerwalls 43 and the positioning pins 33 do not contact the outercircumferential wall 41. This means that even if a large force isapplied to the outer circumferential wall 41 due to the tightening ofthe magnetic tape, resulting in the outer circumferential wall 41deforming so as to become squeezed, the positioning pins 33 that are notin contact with the outer circumferential wall 41 will remain in a statewhere pressure is not applied from the outer circumferential wall 41 dueto the squeezing. Also, even if the inner walls 43 that are fixed viathe bosses 42 to the outer circumferential wall 41 deform so as to movetoward the inside due to the squeezing of the outer circumferential wall41, the positioning pins 33 that contact the outer surfaces 43 a of theinner walls 43 maintain a state where pressure is not applied to theinner walls 43 due to the squeezing. Accordingly, with the tape reel 3,since it is possible to reliably prevent deformation of the first flange21 and the second flange 23 due to pressure applied to the joining pins32 and/or the positioning pins 33, it is possible to reliably preventcontact between the sides of a magnetic tape and the first flange 21 andthe second flange 23 in a state where the magnetic tape has been woundon.

In this way, according to the tape reel 3 and the information recordingmedium 1, the cylindrical body 22 is constructed so as to include thebosses 42, in which the through-holes 42 a through which the joiningpins 32 erected on the first flange 21 are inserted are formed, and theinner walls 43, the second flange 23 is constructed so as to include theprotruding portions 52 including the through-holes 52 a through whichthe joining pins 32 are inserted, and a plurality of the positioningpins 33 that contact the outer surfaces 43 a of the inner walls 43 toposition the cylindrical body 22 are formed on the first flange 21. Bydoing so, even if the outer circumferential wall 41 has deformed so asto become squeezed due to pressure applied by tightening of a magnetictape when the magnetic tape is wound on, it is possible to maintain astate where pressure is not applied to the joining pins 32 and thepositioning pins 33. Therefore, according to the tape reel 3 and theinformation recording medium 1, since it is possible to reliably preventdeformation of the first flange 21 and the second flange 23 due topressure being applied to the joining pins 32 and/or the positioningpins 33, it is possible to reliably prevent contact between the sides ofa magnetic tape and the first flange 21 and second flange 23 when themagnetic tape is wound on.

Also, according to the tape reel 3 and the information recording medium1, the edge portion 51 a of the second flange 23 is formed in acylindrical shape so as to protrude toward the first flange 21 and fitinside the outer circumferential wall 41 of the cylindrical body 22, theprotruding portions 52 are formed on the front end portion of the edgeportion 51 a, and the cylindrical body 22 and the second flange 23 arejoined in a state where the end surfaces 42 d, 43 d on the second flange23 side of the bosses 42 and the inner walls 43 and the protrudingportions 52 are in contact and the end surface 41 d on the second flange23 side of the outer circumferential wall 41 and the inner surface 23 aof the second flange 23 are apart. By doing so, even if the secondflange 23 is pressed onto the cylindrical body 22 when the first flange21, the cylindrical body 22, and the second flange 23 are joined, apressing force in the direction from the first flange 21 toward thesecond flange 23 does not act from the outer circumferential wall 41 ofthe cylindrical body 22 onto the second flange 23. This means it ispossible to sufficiently suppress deformation where the outercircumferential edge of the second flange 23 becomes outwardly openedaway from the outer circumferential edge of the first flange 21. As aresult, according to the tape reel 3 and the information recordingmedium 1, it is possible to reliably avoid a situation where, due to theouter circumferential edge of the second flange 23 being outwardlyopened, a magnetic tape becomes wound on the tape reel 3 in a statewhere the ends in the width direction of the magnetic tape are notaligned (a state where the tape reel 3 is not properly wound on with theend portions of the magnetic tape in alignment), which can causecreasing of the tape, improper rotation of the tape reel,recording/reproduction errors, and the like.

Also, according to the tape reel 3 and the information recording medium1, a construction is used where the thickened portion 21 c thatprotrudes toward the second flange 23 and fits inside the outercircumferential wall 41 of the cylindrical body 22 is formed on theinner surface 21 a of the first flange 21 and the cylindrical body 22and the first flange 21 are joined in a state where the end surfaces 42c, 43 c on the first flange 21 side of the bosses 42 and the inner walls43 contact the thickened portion 21 c and the end surface 41 c on thefirst flange 21 side of the outer circumferential wall 41 and the innersurface 21 a of the first flange 21 are apart. By doing so, even if thecylindrical body 22 is pressed onto the first flange 21 when the firstflange 21, the cylindrical body 22, and the second flange 23 are joined,the pressure will act upon the thickened portion 21 c that has highrigidity, making it possible to sufficiently suppress deformation wherethe outer circumferential edge of the first flange 21 becomes outwardlyopened away from the outer circumferential edge of the second flange 23.As a result, according to the tape reel 3 and the information recordingmedium 1, it is possible to reliably prevent a situation where creasingof the tape, improper rotation of the tape reel, recording/reproductionerrors, and the like occur due to the outer circumferential edge of thefirst flange 21 becoming outwardly opened.

Also according to the tape reel 3 and the information recording medium1, by fixing each inner wall 43 to the outer circumferential wall 41 viatwo bosses 42, it is possible to sufficiently increase the strength ofthe inner walls 43.

Note that the tape reel is not limited to the construction describedabove and can be modified as appropriate. For example, in place of thesecond flange 23 described above, it is possible to apply the presentinvention to a tape reel including the second flange 123 shown in FIG.13. Note that in the following description, component elements that arethe same as the second flange 23 described above have been assigned thesame reference numerals and duplicated description thereof is omitted.As shown in FIG. 13, on the second flange 123, a plurality of (forexample, six) protruding portions 152 including through-holes 52 a areformed on the edge portion 51 a of the opening 51. Also, a positioningpin 153 that contacts the outer surface 43 a of an inner wall 43 of thecylindrical body 22 to position the cylindrical body 22 in a state wherethe second flange 123 contacts the cylindrical body 22 is individuallyformed on the inner surface (i.e., the nearer surface in the plane ofthe paper for FIG. 13, a surface positioned on the cylindrical body 22side when the tape reel has been assembled) of each protruding portion152 (making a total of six positioning pins 153). That is, with thistape reel, positioning pins are formed on both the first flange 21 andthe second flange 23. According to this construction, it is possible tomore reliably position the cylindrical body 22 with respect to the firstflange 21 and the second flange 23.

It is also possible to use a construction where the positioning pins 33of the first flange 21 described above are omitted, that is, aconstruction where the positioning pins 153 are provided only on thesecond flange 123. Also, with the construction described above, althoughboth the end surfaces 42 d on the second flange 23 side of the bosses 42and the end surfaces 43 d on the second flange 23 side of the inner wall43 contact the protruding portions 52 when the first flange 21, thecylindrical body 22, and the second flange 23 are joined, it is alsopossible to use a construction where only one of the end surfaces 42 dand the end surfaces 43 d contact the protruding portions 52. Also, withthe construction described above, although both the end surfaces 42 c onthe first flange 21 side of the bosses 42 and the end surfaces 43 c onthe first flange 21 side of the inner wall 43 contact the thickenedportion 21 c when the first flange 21, the cylindrical body 22, and thesecond flange 23 are joined, it is also possible to use a constructionwhere only one of the end surfaces 42 c and the end surfaces 43 ccontact the thickened portion 21 c. Also, not all of the positioningpins 33 need to contact the outer surfaces 43 a of the inner walls 43,and so long as it is possible to position the cylindrical body 22 whenjoining the first flange 21, the cylindrical body 22, and the secondflange 23, such positioning pins 33 may be separated from the outersurface 43 a after joining.

Also, although an example that is adapted to a single reel-typeinformation recording medium 1 has been described above, it is alsopossible to apply the present invention to a two reel-type informationrecording medium such as a video tape.

What is claimed is:
 1. A tape reel comprising a first flange, acylindrical body, and a second flange that are formed as separateobjects, wherein the tape reel is constructed by joining the firstflange, the cylindrical body, and the second flange in a state where aninner surface side of the first flange and an inner surface side of thesecond flange are in contact with the cylindrical body and face oneanother, the first flange includes joining pins erected on the innersurface of the first flange, the cylindrical body includes an outercircumferential wall, bosses which are fixed to the outercircumferential wall on an inside of the outer circumferential wall andin which through-holes through which the joining pins are inserted areformed, and an inner wall which is positioned inside the outercircumferential wall and disposed so as to follow the outercircumferential wall, the second flange has an opening formed in acentral portion thereof and includes a protruding portion that is formedat an edge portion of the opening so as to protrude toward a center ofthe opening and includes through-holes through which the joining pinsare inserted, and on at least one of the first flange and the secondflange, a plurality of positioning pins that contact a surface on anouter circumferential wall side of the inner wall in a state where thecylindrical body is contacted by at least one of the first flange andthe second flange to position the cylindrical body are formed.
 2. Thetape reel according to claim 1, wherein the edge portion of the secondflange is formed in a cylindrical shape that protrudes toward the firstflange and fits inside the outer circumferential wall, the protrudingportion is formed at a front end portion of the cylindrical edgeportion, and the cylindrical body is joined to the second flange in astate where an end surface on a second flange side of at least one ofthe bosses and the inner wall contacts the protruding portion and an endsurface on the second flange side of the outer circumferential wall isapart from the inner surface of the second flange.
 3. The tape reelaccording to claim 1, wherein a thickened portion that protrudes towardthe second flange side and fits inside the outer circumferential wall isformed on the inner surface of the first flange, and the cylindricalbody is joined to the first flange in a state where an end surface onthe first flange side of at least one of the bosses and the inner wallcontacts the thickened portion and an end surface on the first flangeside of the outer circumferential wall is away from the inner surface ofthe first flange.
 4. The tape reel according to claim 1, wherein thepositioning pins are formed on both the first flange and the secondflange.
 5. The tape reel according to claim 1, wherein the bosses andthe inner wall are joined, and the inner wall is fixed to the outercircumferential wall via the bosses.
 6. An information recording mediumcomprising the tape reel according to claim 1.